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<h3 class="section">4.2 Conditional Syntax</h3>

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<p>A conditional in the C preprocessor begins with a <em>conditional
directive</em>: &lsquo;<samp>#if</samp>&rsquo;, &lsquo;<samp>#ifdef</samp>&rsquo; or &lsquo;<samp>#ifndef</samp>&rsquo;.
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